Conventionally, seals having a structure wherein an O-ring, which is a seal rubber, is mounted in a dovetail groove formed on a valve element are known for seal structures of chamber gate parts of semiconductor manufacturing equipment, liquid crystal manufacturing equipment and the like, namely, an open-close part (valve element and valve seat) of a chamber. This aims at preventing the O-ring from becoming loose or falling from the dovetail groove when a valve element and a valve seat are opened and a seal rubber (O-ring) is exposed, and preventing the O-ring from occupying an inappropriate position or place when the lid and the like are closed again (e.g., JP-A-2003-14126).
In recent years, however, along with the scaling up of liquid crystal panels, semiconductor wafers and the like, these kinds of seals have been also scaled up, and placing of seal rubbers in the dovetail grooves has become complicated. In addition, when the valve element and the valve seat are closed for a long time, the seal lip (protruding part of the tip) of the seal rubber is agglutinated with the matching valve seat, which problematically causes falling from the seal rubber from the dovetail groove upon opening.
The present inventor previously proposed a seal structure wherein a seal rubber is placed in a peripheral groove formed in the main surface of a metal body (JP-A-2-253063). This seal has a structure as shown in FIG. 7-FIG. 9, wherein a peripheral groove 11 having an approximately rectangular cross sectional shape is formed in one surface of a ring retainer (metal body) 10 having an approximately rectangular sectional shape, a seal rubber 12 is placed in the peripheral groove 11, counterbores 14 are formed at plural positions on the opposite surface 17, communicating holes 13 communicating each counterbore 14 and the peripheral groove 11 are formed, a retaining rubber 15 is set in each counterbore 14, and each retaining rubber 15 and seal rubber 12 are integrated by a bridge rubber 16 placed in the communicating hole 13, whereby the seal rubber 12 is fixed in the peripheral groove 11. This seal is used as a gasket, rather than being set on one side of two members capable of an open-close movement like the above-mentioned gate seal, and by physically pressing the seal against the matching member, leakage of the object liquid to be sealed is prevented.
The present inventor considered that the seal described in the aforementioned reference (JP-A-2-253063) had a structure that did not permit easy removal of the seal rubber from the groove of the metal body, and therefore, it could be applicable to a gate seal and tried the application. However, when the valve element and the valve seat in the gate seal were closed for a long time, and the seal lip (protruding part of the tip) of the seal rubber was agglutinated with the matching valve seat, a bridge rubber communicating the seal rubber and the retaining rubber problematically got broken upon opening, as mentioned above.
In view of the above-mentioned situation, the problem to be solved by the present invention is to provide a seal which is attached to one member of combinedly openable-closable two members and hermetically seals the gap between the two members by a seal rubber thereof to be pressed to the other member when the two members are closed, wherein, even when the seal rubber is agglutinated with the matching member (the other member), the seal rubber is not removed from the dovetail groove and does not get broken by the opening motion, but can be separated from the matching member, stable seal performance can be obtained for a long time, and even when a large seal is to be formed, a seal rubber can be easily placed in a dovetail groove, particularly, to provide a seal preferable as a gate seal for a chamber gate of semiconductor manufacturing equipment, liquid crystal manufacturing equipment and the like.